The invention is directed to the mesylate dihydrate salts of 5-(2-(4-(1,2-benzisothiazol-3-yl)-1-piperazinyl)ethyl)-6chloro-1,3-dihydro -2H-indol-2-one (hereafter "ziprasidone mesylate dihydrates"), pharmaceutical compositions containing one or both of the ziprasidone mesylate dihydrates, and methods of administering the ziprasidone mesylate dihydrates to treat psychotic diseases. Ziprasidone is a potent antipsychotic agent and is therefore useful for treating various disorders including schizophrenia, anxiety and migraine pain. U.S. Pat. No. 5,312,925 refers to ziprasidone hydrochloride monohydrate, and states that ziprasidone hydrochloride monohydrate is substantially hygroscopically stable, which alleviates potential problems associated with weight changes of the active ingredient during the manufacture of capsules or tablets. U.S. Pat. No. 5,312,925 is herein incorporated by reference in its entirey. Ziprasidone hydrochloride monohydrate, however, has low aqueous solubility and, as a result, is more appropriate for capsule or tablet formulation than for injectable dosage forms.
The ziprasidone mesylate dihydrates also possess hygroscopic stability. The ziprasidone mesylate dihydrates have the added advantage of having significantly greater aqueous solubility than the hydrochloride monohydrate, which makes the mesylate dihydrates more suitable for injectable dosage forms than the hydrochloride monohydrate.